Holders have much more of an immediate price impact, while investors have a distributed price impact in your example.
If you buy or mine all your coins all at once, you're going to move the order book quite a bit (especially if you're old enough to have amassed a decent amount of money). Conversely, investors might do things like dcaing and buying crypto as it drops so they have more of a hedging/balancing effect on the market.
It was never strictly the fact that:
hodler = one lump sum purchase
investor = multiple buys or DCA
Let's not forget that a hodler is just broadly someone who holds bitcoin. Not a group of people with a strict buy strategy.
I normally assume hodlers are people who buy bitcoin for a price that means any newer buys after a certain time barely make an impact in their portfolio.
If you imagine someone putting $15k into bitcoin and getting 100 in 2015 and kept holding until now, that'd be a (potentially extreme) case of someone I'd consider a hodler.
There are definitely going to be gray areas between everything though and there might be a reason some people continue to invest in bitcoin (as apposed to just taking profits if someone did hodl something near that).
Many of the players, from investors to first time buyers, that are buying at this stage don't hold long term. It's when the price of bitcoin starts to climb that the majority of the holders come back in. Once it starts to become mainstream they tend to buy. As the hype wears off a lot of the investors go back to their day jobs.
Yeah, a lot of this is due to market unknowns and complexes with individual retail traders to exclusively be happy with profits and accept little else - there was a discussion I remember from a while ago about trying to get exchanges of actual risk of crypto investments.
